Process of producing a synthetic detergent of good color



United States Patent C PROCESS OF PRODUCING A SYNTHETIC DETERGENT OFGOOD COIDR Herbert Smith Sylvester, Leonia, N. 1., or toColgate-Palmolive Company, a corporation of Delaware No Drawing.Application October 31, 1952, Serial No. 318,081

6 Claims. (CL 160-505) The present invention relates to a process ofproducing a synthetic detergent of good color from water-soluble saltsof organic sulfuric acid reaction products.

In the manufacture of synthetic detergents of the sulfonate and sulfatetypes, organic compounds are treated with a sulfonating agent, e. g.,oleum, to produce an organic sulfuric acid ester or an organic sulfonicacid which is then neutralized with a suitable base to form awater-soluble salt. Frequently the salts so obtained are not as light incolor as desired and a bleaching operation is resorted to in order toobtain products of good color. The present invention provides ableaching operation for producing synthetic detergents of good colorwhich is simple and economical.

In accordance with the invention, the process of producing a syntheticdetergent of good color comprises admixing a water-soluble silicate andan alkaline hypochlorite with an aqueous slurry of a water-soluble saltof an organic sulfuric acid reaction product. The water-soluble silicateand the alkaline hypochlorite exercise a synergistic bleaching of thewater-soluble salt of the organic sulfurica'cid' reaction product, i.e., the bleaching of the syntheticdetergent obtained in the presence ofboth of these agentsis surprisingly greater than could be predicted fromthe effect of each of these agents individually. Moreover, the mixtureof the three ingredients is found to be mudfi'less earr'dswianetanicequipment than a mixture of 'the'detergent and the hypochlorite in theabsence of the silicate. The viscosity of the mixture also isconsiderably lower in the presence of the silicate which is of definiteadvantage in pumping and spray drying rhe-aqueousslum.

The present inventiompa'fiic'ularntility-in'thepreparation of alltylaryl sulfonates of good color but it may also be applied in thepreparation of synthetic detergents of all of the organic sulfuric acidreaction products which, after neutralization, possess detersiveproperties. As those skilled in the art already know, these organicsulfuric acid reaction products which possess detersive properties aregenerally characterized by the presence in the molecule of a higheralkyl chain having about 8 to 22 carbon atoms per molecule, andordinarily preferably within the range of about 12 to 16 carbon atoms.In the case of the alkyl aryl sulfonates, the aryl group may bemononuclear or polynuclear and it may be further substituted with shortalltyl chains or may be substituted with bydroxyl groups or it may beessentially unsubstituted. Typical examples are dodecylbenzenesulfonate, dodecylnaphthalene sulfonate, tetradecyl toluene sulfonate,etc. Another well-known type of synthetic detergent which may be treatedin accordance with the present invention is a water-soluble salt of thesulfuric acid ester of higher fatty acid monoglycerides, such as sodiumsalt of sulfuric acid ester of coconut oil fatty acid monoglycerides. Afurther well-known type of synthetic detergent is the sulfuric acidester of higher fatty alcohols derived from coconut oil or other fattyacids within the range of carbon atoms specified hereinabove. Thesespecific exam- 2,738,365 Patented Mar. 13, 1956 ples of variousdetergents are given purely for the purpose of illustration and not forthe purpose of limitation since the present process is applicable to thepreparation of detergents of good color from sulfuric acid reactionproducts of all organic materials which, after neutralization, possessdetersive properties.

Any of the alkaline metal hypochlorites may be used in the process ofthe present invention but, generally speaking, sodium hypochlorite ismuch preferred because of its effectiveness, its relatively low cost,and the fact that most detergent compositions which will be treated inaccordance with the present invention are sodium salts of the sulfuricacid reaction product. Other hypochlorites which may be usedsatisfactorily include lithium h hl grite and potassium h o c hlorite.wi 5 0mm.- silicates mcli ar e sed in the process of the presentinvention may be any of the alkaline silicates including sodium andpotassium silicate but in general it is preferred to use sodium silicatebecause of its effectiveness, its relatively low cost, and the fact thatmost of the detergents which will be treated in accordance with thepresent invention are sodium salts of the organic sulfuric acid reactionproducts. While any water-soluble alkaline silicate may be used, certainratios of the alkaline oxide to silicon dioxide are found to be ofparticular advantage. In the case of sodium silicate the NazOzSiOz ratiomay vary from about 1 22 to 1:3.25.

The amount of water 'soluble silicate, based upon the quantity ofsynthetic detergent solids used, may vary from a small but effectiveamount of the order of about 1% up to any desired amount present in thecomposition. Generally speaking, about 5 to 10% of silicate is themaximum amount required in the composition for controlling the viscosityand for protecting the equipment against corrosion and for exercisingits synergistic effect with the sodium hypochlorite in the bleaching ofthe detergent. The amount of hypochlorite used may also vary widely froma small but effective amount of the order of about 0.1% up to about 5%by weight of the active ingredient. These ratios are not critical in thesense that there is a sudden change in the bleaching efiect below orabove the indicated range but within the indicated range good resultsare assured by following the process of the present invention. While itis preferred that the silicate be admixed with the detergent slurryprior to the introduction of the hypochlorite material, this order ofaddition is not absolutely essential and they may be introducedsimultaneously or the hypochlorite may be introduced a short period oftime prior to the introduction of the silicate but inasmuch as thehypochlorite may cause some corrosion in the apparatus prior to theintroduction of the silicate, this order of addition is not preferred.

The process may be carried out batchwise or continuously.

In carrying out the process of the invention batchwise, a slurry of thewater-soluble salt of the sulfuric acid reaction product in water isplaced in a suitable vessel, e. g., a vessel made of austeniticstainless steel, and the formula amount of silicate is then admixedtherewith by any convenient stirring or agitating mechanism. When thesilicate has been blended with the aqueous slurry of the syntheticdetergent material, the sodium hypochlorite is then introduced withthorough mixing. The bleaching effect is produced by the joint presenceof the silicate and the hypochlorite and the resulting composition,after standing for a suitable time to permit the reaction to go at leastsubstantially to completion, is then ready for procg wwewiment. The timeis not critisince the major proportion of the bleaching is accomplishedrelatively quickly; e. g., in 30 to minutes, but longer periods up toseveral hours may be used, if de- 3 sired. Generally speaking, thesedetergents are prepared in M dried form and the treated composition asde- I- 1. ready for admixing in a suitable crutcher with otheringredients desired in the final composition and for spray drying.

In the continuous process a stream of the aqueous slurry of thesynthetic detergent is pumped through a line from a suitable storagetank to a suitable receiving tank. Into this flowing stream of theaqueous slurry of the detergent material a stream of silicate is pumpedwith suitable proportioning means so as to introduce the silicatematerial into the stream of detergent at a rate calculated to give theformula proportions of these two ingredients in the mixed stream.Thereafter a proportioned stream of the solium hyprochlorite is pumpedinto the mixture of silicate and detergent at a rate calculated tointroduce the formula amount of hypochlorite into the mixture. The flowconditions in the pipe must be regulated so as to give good stirringeither inherently fmm turbulent flow or aided by mechanical stirringdevices in the line. The mixture of three ingredients goes into thereceiving tank where it is held for a time sufficient at leastsubstantially to complete the reaction before it is pumped to thecrutcher for further processing.

The following table illustrates the synergistic efiect of the treatmentof an aqueous slurry of synthetic detergent material (50% by weight ofwater and 50% by weight of detergent solids) with sodium hyprochloriteand sodium silicate jointly as compared with the effects of treatment ofthe same material with these agents individually, the time of treatmentin each case being three hours:

The N-silicate referred to in the foregoing table was added as anaqueous solution or slurry containing approximately 38% solids and theratio of NazOzSiOa was 1:3.22. The synthetic detergent was the sodiumsalt of dodecyl benzene sulfonate obtained by polymerizing propylene toobtain the tetramer, condensing this polypropylene with benzene,sulfonating the condensate and neutralizing the sulfonic acid. Thedetergent was about 88% active ingredient and 12% sodium sulfate.

When the silicate is present, the proportion of sodium hypochloriterequired to produce a given bleaching effect, as noted in the table, isvery materially reduced as compared with the proportion required when nosodium silicate is present at the time of treatment. This clearlydemonstrates the synergistic efiect of the silicate upon thehypochlorite since the effect of the silicate itself on the alkyl arylsulfonate was relatively slight.

5 The following table illustrates the eifect of the silicate on theviscosity of a 50% aqueous slurry of the same type of syntheticdetergent referred to in Table I:

1 Determined in a Brooktield viscosimeter.

Having thus described the invention, what is claimed is: 1. The processof producing a synthetic detergent of good color which comprisesadmixing a water-soluble alkali metal silicate and an alkali metalhypochlorite with an aqueous slurry of a water-soluble salt of anorganic sulfuric acid rection product possessing detersive properties,said ilicate and h hlorite being used in amounts ient t e ea ng c saidsalt and a reduction in viscosit 0 said aqueous slurry of organic sul 1cacid reaction product.

2. The process as set forth in claim 1 in which the water-soluble saltis an alkyl aryl sulfonate.

3.Theprocessassetforthinclaimlinwhichthe water-soluble silicate is asodium silicate having an NazOzSiOz ratio of about 1:2 to 1:33.25.

4. The process as set forth in claim 1 in which the alkalinehypochlorite is sodium hypochlorite.

5. The process as set forth in claim 1 in which the water-solublesilicate is used within a range from a small but effective amount up toabout 10% by weight of the water-soluble salt.

6. The process as set forth in claim 1 in which the alkali metalhypochlorite is used within a range from a small but effective amount upto about 5% of the watersoluble salt.

References Cited in the file of this patent UNITED STATES PATENTS1,931,245 Banigan Oct. 17, 1933 2,333,830 Toone Nov. 9, 1943 2,566,501Smith et al Sept. 4, 1951 OTHER REFERENCES Carter: Ind. and Eng. Chem.,vol. 18 (1926), pp. 248-252.

SchwartbPerry: Surface Active Agents (1949), p. 123.

1. THE PROCESS OF PRODUCING A SYNTHETIC DETERGENT OF GOOD COLOR WHICHCOMPRISES ADMIXING A WATER-SOLUBLE ALKALI METAL SILICATE AND AN ALKALIMETAL HYPOCHLORITE WITH AN AQUEOUS SLURRY OF A WATER-SOLUBLE SALT OF ANORGANIC SULFURIC ACID RECTION PRODUCT POSSESSING DETERSIVE PROPERTIES,SAID SILICATE AND HYPROCHLORITE BEING USED IN AMOUNTS SUFFICIENT TOEFFECT BLEACHING OF SAID SALT AND A REDUCTION IN VISCOSITY OF SAIDAQUEOUS SLURRY OF ORGANIC SULFURIC ACID REACTION PRODUCT.